<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
	<head>
	<meta charset="UTF-8">
	<title>Insert title here</title>
	</head>
	<body>
		<%--EL 表达式还能做一些简单的运算 --%>
		<%
			pageContext.setAttribute("num1", 10);
			pageContext.setAttribute("num2", 9);
			request.setAttribute("a", true);
			request.setAttribute("b", false);
			String str1 = "";
			String str2 = "Hello wrold";
			session.setAttribute("str1", str1);
			session.setAttribute("str2", str2);
		%>
		
		${num1 > num2 }
		<hr>
		${a && b }
		<hr>
		<%--也可以这么写，其实每一个运算符都有相对应的单词 --%>
		${a and b }
		<hr>
		${a or b }
		<hr>
		<%--判断是否为空 --%>
		${empty str1 }
		<hr>
		${empty str2 }
	</body>
</html>